Radio ic device

ABSTRACT

A radio IC device includes an electromagnetic coupling module includes a radio IC chip arranged to process transmitted and received signals and a feed circuit board including an inductance element. The feed circuit board includes an external electrode electromagnetically coupled to the feed circuit, and the external electrode is electrically connected to a shielding case or a wiring cable. The shielding case or the wiring cable functions as a radiation plate. The radio IC chip is operated by a signal received by the shielding case or the wiring, and the answer signal from the radio IC chip is radiated from the shielding case or the wiring cable to the outside. A metal component functions as the radiation plate, and the metal component may be a ground electrode disposed on the printed wiring board.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to radio IC devices, and particularly to aradio IC device including a radio IC used for an RFID (Radio FrequencyIdentification) system.

2. Description of the Related Art

A RFID system has been developed for commodity management in recentyears. In the RFID system, information is transmitted by non-contactcommunication between a reader/writer that generates an induction fieldand an IC chip (may be referred to as IC tag or radio IC chip) whichstores commodity information and other information attached on thepackage or other item of the commodity.

Japanese Unexamined Patent Application Publication No. 2002-232221discloses a transmitter/receiver unit including an IC chip-includingradio IC device together with other chip components. In thetransmitter/receiver unit, a circuit board on which the IC chip ismounted is enclosed in a shielding case, and an antenna element isfurther disposed on the circuit board.

However, since the antenna element is disposed as an independentcomponent different from the radio IC chip within the shielding case,the radio IC device is relatively large and, consequently, the size ofthe transmitter/receiver unit is increased. In order to avoid theincrease in size, the antenna element is miniaturized. However, thisreduces the radiation characteristics of the antenna element, whichcauses problems, such as a decrease in communication distance.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of thepresent invention provide a radio IC device that is miniaturized withoutreducing the radiation characteristics.

A radio IC device according to a preferred embodiment of the presentinvention includes a high frequency device defined by an electromagneticcoupling module or a radio IC chip, and a radiation plate arranged so asto be coupled to the high frequency device. The electromagnetic couplingmodule includes a radio IC arranged to process transmitted and receivedsignals and a feed circuit board including a feed circuit having aninductance element connected to or electromagnetically coupled to theradio IC and coupled to an external circuit. The radiation electrode ispreferably defined by a case of an apparatus and/or a metal componentdisposed in the apparatus, for example.

More specifically, the radio IC device includes a high frequency deviceand a radiation plate, and the high frequency device includes anelectromagnetic coupling module or a radio IC chip. The electromagneticcoupling module may preferably include a feed circuit board includingthe radio IC, or a feed circuit board on which the radio IC is disposed.If the high frequency device is a radio IC chip, the radio IC chip andthe radiation plate are coupled to each other with a coupling electrode,such as a loop electrode.

The metal component defining the radiation plate can be any metalportion, such as a wiring electrode disposed in an apparatus, ashielding case, a ground electrode, and a metal portion of a connector,or a metal case of a switching module used in the apparatus, forexample.

The feed circuit board may preferably include a resonance circuit and/ora matching circuit. The radio IC is operated by a signal received by theradiation plate through the resonance circuit and/or the matchingcircuit, and the answer signal from the radio IC is radiated from theradiation plate to the outside through the resonance circuit and/or thematching circuit.

Since the case of the apparatus and/or any metal component in theapparatus can be used as the radiation plate, another component is notrequired to be provided as an antenna element. Consequently, the size ofthe apparatus is not increased. In addition, the metal components, suchas the case, the wiring electrode, and the ground electrode arerelatively large, and accordingly, desired radiation characteristics canbe obtained. The apparatus used herein preferably refers to anelectronic apparatus in which the radio IC device is to be mounted, suchas cellular phone, for example. If the case of the apparatus is ashielding case made of a metal, the case can function as the radiationplate by itself. If the case is made of a non-conductive material, anelectroconductive electrode film can be formed on the case so that theelectrode film functions as the radiation plate.

In the radio IC device, a miniature radio IC chip can easily be mountedon a small feed circuit board by providing an electromagnetic couplingmodule including a radio IC chip disposed on a feed circuit board. Ifthe radio IC is modified according to the working frequency of the RFIDsystem, all that is required is to modify the design of the feed circuitof the feed circuit board. It is not necessary to change the shape, sizeor arrangement of the radiation plate or the coupling state between theradiation plate and the feed circuit board.

The radio IC device according to preferred embodiments of the presentinvention does not require that an antenna element be disposed as anadditional independent component. Thus, the radio IC device andapparatuses including the radio IC device can be miniaturized withoutdegrading the radiation characteristics. The feed circuit board can havea relatively small size. Accordingly, even a very small radio IC chipcan be easily mounted on the small feed circuit board with aconventionally used IC mounter. Consequently, the packaging cost isreduced. All that is required to change the working frequency is tomodify the design of the feed circuit.

Other features, elements, steps, characteristics and advantages of thepresent invention will become more apparent from the following detaileddescription of preferred embodiments of the present invention withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a radio IC device according to a preferredembodiment of the present invention.

FIG. 2 is a sectional view showing the connection between anelectromagnetic coupling module and a wiring electrode.

FIG. 3 is a perspective view of a radio IC chip.

FIG. 4 is a perspective view showing the connection between the wiringelectrode and a case.

FIG. 5 is a sectional view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 6 is a perspective view showing the connection from anelectromagnetic coupling module and a wiring case.

FIG. 7 is an exploded perspective view of a feed circuit board includinga resonance circuit according to a preferred embodiment of the presentinvention.

FIG. 8 is a plan view a feed circuit board including a resonance circuitaccording to another preferred embodiment of the present invention.

FIG. 9 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 10 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 11 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 12 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 13 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 14 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 15 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 16 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 17 is an exploded perspective view of a radio IC device accordingto another preferred embodiment of the present invention.

FIG. 18 is a perspective view of the preferred embodiment shown in FIG.17.

FIG. 19 is a sectional view of the preferred embodiment shown in FIG.17.

FIG. 20 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 21 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 22 is a perspective view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 23 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 24 is a plan view of the radio IC device according to the preferredembodiment shown in FIG. 23 in the course of manufacture.

FIG. 25 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 26 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 27 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 28 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 29 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 30 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 31 is a plan view illustrating the operation principle of the radioIC device according to the preferred embodiment shown in FIG. 30.

FIG. 32 is a sectional view taken along line A-A in FIG. 30.

FIG. 33 is a sectional view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 34 is a sectional view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 35 is a sectional view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 36 is an assembly diagram of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 37 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 38 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 39 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 40 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 41 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 42 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 43 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 44 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 45 is a sectional view taken along line B-B in FIG. 44.

FIG. 46 is a sectional view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 47 is a sectional view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 48 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 49 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 50 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 51 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 52 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 53 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 54 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 55 is a sectional view taken along line C-C in FIG. 54.

FIG. 56 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 57 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 58 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 59 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 60 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 61 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 62 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 63 is a plan view illustrating the operation principle of the radioIC device according to the preferred embodiment shown in FIG. 62.

FIG. 64 is a perspective view of an electromagnetic coupling module ofthe radio IC device according to the preferred embodiment shown in FIG.62.

FIG. 65 is a sectional view of the electromagnetic coupling module shownin FIG. 62.

FIG. 66 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 67 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 68 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 69 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 70 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 71 is a plan view of a radio IC device according to a 55thpreferred embodiment of the present invention.

FIG. 72 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

FIG. 73 is a plan view of an electromagnetic coupling module of theradio IC device according to the preferred embodiment shown in FIG. 73

FIG. 74 is a plan view of an electromagnetic coupling module accordingto a modification of a preferred embodiment, used in a radio IC deviceaccording to the present invention.

FIG. 75 is a plan view of a radio IC device according to anotherpreferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the radio IC device according to the presentinvention will now be described with reference to the attached drawings.The same elements and portions in the drawings are designated by thesame reference numerals, and the same description is not repeated.

First Preferred Embodiment

FIG. 1 shows portions of an electronic apparatus including a radio ICdevice according to a first preferred embodiment of the presentinvention. The electronic apparatus includes a printed wiring board 20on which an electromagnetic coupling module 1 and other electroniccomponents 26, such as a chip resistor and a chip capacitor, forexample, are mounted. The printed wiring board also includes a shieldingelectrode 27 therein.

The electromagnetic coupling module 1 preferably includes a radio ICchip 5 processing a transmitted/received signal having a predeterminedfrequency and a feed circuit board 10 on which the radio IC chip 5 isdisposed, as shown in FIG. 2. A shielding case 28 of an apparatus alsodefines a radiation plate that functions as an antenna element, and iselectrically connected to second wiring electrodes 21 a and 21 b (seeFIGS. 2 and 4) magnetically coupled to the electromagnetic couplingmodule 1 on the printed wiring board 20. The electromagnetic couplingmodule 1 and the radiation plate (shielding case 28) define the radio ICdevice.

The radio IC chip 5 preferably includes a clock circuit, a logiccircuit, a memory circuit and other circuit elements, and storesnecessary information. On the rear surface of the radio IC chip,input/output terminal electrodes 6 and packaging terminal electrodes 7are disposed, as shown in FIG. 3. The input/output terminal electrodes 6are electrically connected to electrodes 12 a and 12 b (see FIGS. 7 and8) disposed on the surface of the feed circuit board 10 preferablythrough metal bumps 8, for example. The packaging terminal electrodes 7are electrically connected to electrodes 12 c and 12 d through the metalbumps 8. The material of the metal bumps 8 can preferably be Au, Ag,solder or other suitable material, for example.

A protective film 9 is provided between the surface of the feed circuitboard 10 and the rear surface of the radio IC chip 5 to improve thebonding strength between the feed circuit board 10 and the radio IC chip5 and to protect the bumps 8.

The shielding case 28 is preferably made of a metal and arranged so asto cover the electromagnetic coupling module 1 and the electroniccomponents 26 on the printed wiring board 20. In addition, the shieldingcase functions as a radiation plate of the electromagnetic couplingmodule 1, as will be described below. If the case 28 is made of anonconductive material, an electroconductive electrode film 28′ ispreferably formed on the internal surface of the case 28, as indicatedby oblique lines shown in FIG. 4, and the electrode film 28′ functionsas the radiation plate.

The feed circuit board 10 includes a feed circuit (including a resonancecircuit having an inductance element and a matching circuit, not shownin FIG. 2), and is provided with external electrodes 19 a and 19 b fromthe rear surface to the sides. Also, the connection electrodes 12 a and12 d (see FIGS. 7 and 8) are provided on the surface of the feed circuitboard 10. The external electrodes 19 a and 19 b are electromagneticallycoupled to the resonance circuit included in the feed circuit board 10and electrically connected to the second wiring electrodes 21 a and 21 bwith an electroconductive adhesive 29. The electrical connection maypreferably be established by soldering, for example.

More specifically, the feed circuit board 10 includes a resonancecircuit having a predetermined resonance frequency that transmits asignal having the predetermined frequency generated from the radio ICchip 5 to the shielding case 28 (or the electrode film 28′) through theexternal electrodes 19 a and 19 b and the wiring electrodes 21 a and 21b, and supplies a signal having the predetermined frequency selectedfrom the signals received by the shielding case 28 (or the electrodefilm 28′) to the radio IC chip 5. In the radio IC device, the radio ICchip 5 operates according to the signal received by the shielding case(or the electrode film 28′), and an answer signal from the radio IC chip5 is radiated from the shielding case 28 (or the electrode film 28′).

In the electromagnetic coupling module 1, the external electrodes 19 aand 19 b disposed on the surface of the feed circuit board 10 areelectromagnetically coupled to the resonance circuit included in thefeed circuit board 10 and electrically connected to the shielding case28 which functions as an antenna. The electromagnetic coupling module 1does not require a separate, relatively large antenna element, andaccordingly the electromagnetic coupling module can be very small. Sincethe feed circuit board 10 has been miniaturized, the radio IC chip 5 canpreferably be mounted on a miniaturized feed circuit board 10 by aconventionally used IC mounter or other suitable mounter, for example,and thus, the packaging cost can be reduced. All that is required tochange the working frequency is to modify the design of the feedcircuit, and the shielding case 28 may be used without being modified.The shielding case 28 is relatively large and can ensure desiredradiation characteristics.

Preferably, the electroconductive adhesive 29 used to bond the externalelectrodes 19 a and 19 b with the second wiring electrodes 21 a and 21 bincludes metal particles. Such an adhesive 29 exhibits a smalldifference in thermal expansion from the external electrodes 19 and 19 band the wiring electrodes 21 a and 21 b when undergoing temperaturechanges, and accordingly, the bonding reliability is improved.

The second wiring electrodes 21 a and 21 b may be provided within theprinted wiring board 20. In this instance, the second wiring electrodes21 a and 21 b are electrically connected to the electrodes on thesurface of the wiring board 20 through a known via hole conductor. Theprinted wiring board 20 may preferably be a ceramic multilayer substrateor a resin substrate, for example.

Second Preferred Embodiment

FIG. 5 shows essential portions of an electronic apparatus including aradio IC device according to a second preferred embodiment of thepresent invention. The electronic apparatus includes a plurality ofprinted wiring boards 31 and 32 covered with a case 33. The printedwiring boards 31 and 32 are disposed on a substrate 30. One printedwiring board 31 is provided with an electromagnetic coupling module 1and other electronic components thereon, and the other printed wiringboard 32 is provided with other electronic components thereon.

In the electromagnetic coupling module 1, the external electrodes 19 aand 19 b (see FIG. 2) of the electromagnetic coupling module 1 areelectrically connected to second wiring electrodes 21 a and 21 bdisposed on the printed wiring board 31, as shown in FIG. 6. The wiringelectrodes 21 a and 21 b are connected to one end of a wiring cable 36defining a first wiring electrode provided to a known wiring connector35. The other end of the wiring cable 36 is fixed to a securing member37 disposed on the printed wiring board 32 and is electrically open.

In the second preferred embodiment, the wiring cable 36 between thewiring boards 31 and 32 functions as a radiation plate of theelectromagnetic coupling module 1. Thus, an RFID system is defined, andtransmits and receives high-frequency signals to and from areader/writer. Thus, the same effects are produced as in the firstpreferred embodiment.

First Preferred Embodiment of Resonance Circuit

FIG. 7 shows a resonance circuit according to a first preferredembodiment, in which the feed circuit board 10 includes the resonancecircuit. The feed circuit board 10 is preferably prepared by stackingdielectric ceramic sheets 11A to 11H, and pressing and firing the stack.The sheet 11A is provided with connection electrodes 12 a and 12 b,electrodes 12 c and 12 d, and via hole conductors 13 a and 13 b. Thesheet 11B is provided with a capacitor electrode 18 a, conductorpatterns 15 a and 15 b, and via hole conductors 13 c to 13 e. The sheet11C is provided with a capacitor electrode 18 b and via hole conductors13 d to 13 f. The sheet 11D is provided with conductor patterns 16 a and16 b and via hole conductors 13 e, 13 f, 14 a, 14 b and 14 d. The sheet11E is provided with conductor patterns 16 a and 16 b and via holeconductors 13 e, 13 f, 14 a, 14 c and 14 e. The sheet 11F is providedwith a capacitor electrode 17, conductor patterns 16 a and 16 b and viahole conductors 13 e, 13 f, 14 f and 14 g. The sheet 11G is providedwith conductor patterns 16 a and 16 b and via hole conductors 13 e, 13f, 14 f and 14 g. The sheet 11H is provided with conductor patterns 16 aand 16 b and a via hole conductor 13 f.

By stacking these sheets 11A to 11H, a conductor pattern 16 a ispreferably provided in a spiral arrangement, for example, continuingthrough the via hole conductors 14 c, 14 d and 14 g, thus defining aninductance element L1, and a conductor pattern 16 b is preferablyprovided in a spiral arrangement, for example, continuing through thevia hole conductors 14 b, 14 e and 14 f, thus defining an inductanceelement L2. Also, a capacitance element C1 is defined by capacitorelectrodes 18 a and 18 b, and a capacitance element C2 is defined bycapacitor electrodes 18 b and 17.

One end of the inductance element L1 is connected to the capacitorelectrode 18 b through the via hole conductor 13 d, conductor pattern 15a and the via hole conductor 13 c, and one end of the inductance elementL2 is connected to the capacitor electrode 17 through the via holeconductor 14 a. The other ends of the inductance elements L1 and L2 arebrought together on the sheet 11H and connected to the connectionelectrode 12 a through the via hole conductor 13 e, the conductorpattern 15 b and the via hole conductor 13 a. In addition, the capacitorelectrode 18 a is electrically connected to the connection electrode 12b through the via hole conductor 13 b.

The connection electrodes 12 a and 12 b are electrically connected tothe input/output terminal electrodes 6 (see FIG. 3) of the radio IC chip5 through the metal bumps 8 (see FIG. 2). The electrodes 12 c and 12 dare connected to the packing terminal electrodes 7 of the radio IC chip5.

In addition, the external electrodes 19 a and 19 b are provided on therear surface of the feed circuit board 10 preferably by applying aconductive paste, for example. The external electrode 19 a is coupled tothe inductance elements L (L1 and L2) by a magnetic field, and theexternal electrode 19 b is connected to the capacitor electrode 18 bthrough the via hole conductor 13 f. The external electrodes 19 a and 19b are electrically connected to the wiring electrodes 21 a and 21 b, asdescribed above.

In the resonance circuit, the inductance elements L1 and L2 are arrangedsuch that two conductor patterns 16 a and 16 b are disposed in parallelor substantially in parallel. The two conductor patterns 16 a and 16 bpreferably have different line lengths from each other so as to havedifferent resonance frequencies. Thus, the radio IC device can be usedfor a wide range of frequencies.

The ceramic sheets 11A to 11H may be made of a magnetic ceramicmaterial, and the feed circuit board 10 can be easily produced by aknown process for forming a multilayer substrate, such as stackingsheets or printing into a thick film, for example.

The sheets 11A to 11H may preferably be flexible sheets made of, forexample, a dielectric material such as polyimide or liquid crystalpolymer. Electrodes or conductors are formed on such flexible sheets bya thick film forming process, for example, and then the sheets arestacked one on top of another and thermally compressed into a multilayercomposite. Thus, the inductance elements L1 and L2 and the capacitanceelements C1 and C2 may be disposed within the circuit board.

In the feed circuit board 10, the inductance elements L1 and L2 and thecapacitance elements C1 and C2 are disposed at different positions whenviewed from above. The inductance elements L1 and L2 are coupled to theexternal electrode 19 a (wiring electrode 21 a) by a magnetic field, andthe capacitance element C1 is coupled to the external electrode 19 b(wiring electrode 21 b) by an electric field.

Thus, the electromagnetic coupling module 1 including the radio IC chip5 on the feed circuit board 10 receives high-frequency signals (forexample, UHF frequencies) radiated from a reader/writer (not shown) witha shielding case 28 or a wiring cable 36, so that the resonance circuitcoupled to the external electrodes 19 a and 19 b through the wiringelectrodes 21 a and 21 b by a magnetic field and an electric fieldresonates to supply only a received signal having a predeterminedfrequency to the radio IC chip 5. A predetermined energy is extractedfrom the received signal. The energy is used as a driving source tomatch the information stored in the radio IC chip 5 with a predeterminedfrequency by a resonance circuit, and to transmit the information to theshielding case 28 or the wiring cable 36 through the external electrodes19 a and 19 b and the wiring electrodes 21 a and 21 b, and furthertransmit or transfer the information to the reader/writer from the case28 or the cable 36.

The resonance frequency characteristics of the feed circuit board 10depend on the resonance circuit including the inductance elements L1 andL2 and the capacitance elements C1 and C2. The resonance frequency ofthe signal radiated from the shielding case 28 or the wiring cable 36substantially depends on the self resonant frequency of the resonancecircuit. It is accordingly not necessary to redesign the resonancecircuit even if the shielding case 28 or the wiring cable 36 is changedin shape or material. Thus, the resonance circuit can be applied tovarious electronic apparatuses.

The resonance circuit preferably also defines a matching circuit tomatch the impedances between the radio IC chip 5 and the radiation plate(shielding case 28 or wiring cable 36). The feed circuit board 10 maypreferably include a matching circuit provided in addition to theresonance circuit including the inductance elements and the capacitanceelements (in this sense, the resonance circuit may be referred to asmatching circuit). The design for a resonance circuit also defining amatching circuit tends to be complicated. A structure in which amatching circuit is provided separately from the resonance circuitenables the resonance circuit and the matching circuit to beindependently designed. The resonance circuit may be replaced with amatching circuit. The resonance circuit may be designed in view of theshape and size of the radiation plate, or the shielding case 28 or thewiring cable 36. Although this requires that the feed circuit board 10be precisely mounted at a correct position, the radiationcharacteristics of the resulting radio IC device can be improved.

Second Preferred Embodiment of Resonance Circuit

FIG. 8 shows a resonance circuit according to a second preferredembodiment, in which the resonance circuit is disposed on a feed circuitboard 40. This feed circuit board 40 is preferably made of a flexiblePET film, for example, and on which a spiral conductor pattern 42defining inductance elements L and a capacitor electrode 43 defining acapacitance element C are disposed. Electrodes 12 a and 12 b extendingfrom the conductor pattern 42 and the capacitor electrode 43 areelectrically connected to the terminal electrodes 6 of the radio IC chip5. Electrodes 12 c and 12 d provided on the circuit board defineterminal ground electrodes and are electrically connected to theterminal electrodes 7 of the radio IC chip 5.

The feed circuit board 40 is substantially the same as that of the firstpreferred embodiment in that the inductance elements L and thecapacitance element C define a resonance circuit and are coupled to therespectively opposing second wiring electrodes 21 a and 21 b by amagnetic field and an electric field to transmit and receive ahigh-frequency signal having a predetermined frequency. In the secondpreferred embodiment, in particular, the feed circuit board 40 made of aflexible film produces a thin electromagnetic coupling module 1. Theinductances of the inductance elements L can be varied by varying theline width and/or the line pitch of the conductor pattern 42, and thusthe resonance frequency can be precisely adjusted.

In the second preferred embodiment, the conductor pattern 42 definingthe inductance elements L preferably includes two spiral lines that areconnected to each other at the approximate center of the spirals. Thetwo lines of the conductor pattern 42 have respective inductances L1 andL2 and their resonance frequencies can be set to different values. Thus,the resulting radio IC device can be used in a wide range of frequenciesas that of the first preferred embodiment.

Third Preferred Embodiment

In the radio IC device according to a third preferred embodiment, secondwiring electrodes 22 a and 22 b are preferably configured in ameandering arrangement on the printed wiring board 20 of an electronicapparatus. The electromagnetic coupling module 1 is mounted on one endof each of the wiring electrodes 22 a and 22 b, as shown in FIG. 9. Ametal case 50 of a battery or liquid crystal panel is disposed close tothe electrode 22 b on the printed wiring board 20. The electromagneticcoupling module 1 is coupled to the wiring electrodes 22 a and 22 b insubstantially the same manner as in the first and second preferredembodiments.

In the third preferred embodiment, the second wiring electrodes 22 a and22 b function as the radiation plate, and the metal case 50 via thewiring electrode 22 b is coupled to the wiring electrode 22 b tofunction as the radiation palate. The wiring electrodes 22 a and 22 bthemselves may function as the radiation plate, and, in addition, themetal case 50 is also used as the radiation plate. Consequently, theradiation characteristics and the antenna gain are improved. The radioIC device of the third preferred embodiment can function without themetal case 50. By matching the resonance frequency of the metal case 50to the working frequency of the radio IC device, the antenna gain can befurther improved.

Fourth Preferred Embodiment

The radio IC device according to a fourth preferred embodiment hassubstantially the same structure as that of the third preferredembodiment, except that a portion of the metal case 50 used in the thirdpreferred embodiment is disposed on the wiring electrode 22 b, as shownin FIG. 10. The fourth preferred embodiment produces substantially thesame effects as the third preferred embodiment. Since the metal case 50overlaps the wiring electrode 22 b, particularly, the degree of theircoupling is increased.

Fifth Preferred Embodiment

In the radio IC device according to a fifth preferred embodiment, thewiring electrode 22 a is electrically connected to a ground electrode 23disposed on the printed wiring board 20, and the other wiring electrode22 b is disposed close to the metal case 50, as shown in FIG. 11.

The ground electrode 23 may be included in the printed wiring board 20.In this instance, the wiring electrode 22 a may be connected to theground electrode 23 through a via-hole conductor, or may be configuredto have a meandering arrangement as shown in FIG. 9 and overlap theground electrode 23.

In the fifth preferred embodiment, the wiring electrode 22 b and themetal case 50 function as a radiation plate, and, in addition, theground electrode 23 connected to the wiring electrode 22 a also functionas a radiation plate. Since the ground electrode 23 has a large area,the radiation characteristics and the antenna gain are improved.

Sixth Preferred Embodiment

The radio IC device according to a sixth preferred embodiment hassubstantially the same structure as that of the fifth preferredembodiment except that a portion of the metal case 50 used in the fifthpreferred embodiment is disposed on the wiring electrode 22 b, as shownin FIG. 12. The sixth preferred embodiment produces substantially thesame effects as the fifth preferred embodiment. Since the metal case 50overlaps the wiring electrode 22 b, particularly the degree of theircoupling is increased.

Seventh Preferred Embodiment

In the radio IC device according to a seventh preferred embodiment, aloop electrode 24 defining the second wiring electrode is disposed onthe printed wiring board 20, and the electromagnetic coupling module 1is disposed on both ends of the line of the loop electrode 24, as shownin FIG. 13. The metal case 50 is disposed close to the loop electrode 24on the printed wiring board 20. The electromagnetic coupling module 1 iscoupled to the loop electrodes 24 in substantially the same manner as inthe first and the second preferred embodiment.

In the seventh preferred embodiment, the loop electrode 24 functions asa radiation plate, and the metal case coupled to the loop electrode 24also functions as a radiation plate. In particular, the loop electrode24 can match the impedances between the radio IC chip 5 and theradiation plate, and thus improves the signal transmission efficiencybetween the radio IC chip 5 and the radiation plate without requiring anadditional matching portion.

Eight Preferred Embodiment

In the radio IC device according to an eighth preferred embodiment, themetal case 50 used in the sixth preferred embodiment (see FIG. 12) isdisposed on the rear surface of the printed wiring board 20, as shown inFIG. 14. A portion of the metal case 50 is coupled to the wiringelectrode 22 b with the printed wiring board 20 therebetween. The otherstructure is substantially the same as in the sixth preferredembodiment. The eighth preferred embodiment produces substantially thesame effects as the sixth preferred embodiment. Since the metal case 50is disposed on the rear surface of the printed wiring board 20, theground electrode 23 can be provided with a large area.

Ninth Preferred Embodiment

In the radio IC device according to a ninth preferred embodiment,another metal case 51 is included close to the wiring electrode 22 a onthe surface of the printed wiring board 20 of the third preferredembodiment (see FIG. 9), as shown in FIG. 15. The metal case 51 iscoupled to the wiring electrode 22 a to function as a radiation plate,and, thus, the antenna gain is further improved.

Tenth Preferred Embodiment

In the radio IC device according to a tenth preferred embodiment, themetal case 51 used in the ninth preferred embodiment is disposed on therear surface of the printed wiring board 20, as shown in FIG. 16. Inthis instance, the metal case is coupled to the wiring electrode 22 awith the printed wiring board 20 therebetween.

Eleventh Preferred Embodiment

In the radio IC device according to an eleventh preferred embodiment,the printed wiring board 20 is enclosed by an upper and a lower metalcase 52 and 53, as shown in FIGS. 17 and 18, and the metal cases 52 and53 function as radiation plates. Wiring electrodes 22 a and 22 b areprovided on the printed wiring board 20 and coupled to theelectromagnetic coupling module 1. The wiring electrode 22 a is disposedon the rear side and connected to the front side through a via holeconductor. The wiring electrode 22 b is disposed on the front side.

As shown in FIG. 19, in addition, the metal case 52 has a couplingconductor 52 a to enable the metal case 52 to couple efficiently to thewiring electrode 22 b, and the metal case 53 has a coupling conductor 53a to enable the metal case 53 to couple efficiently to the wiringelectrode 22 a.

In the eleventh preferred embodiment, the wiring electrodes 22 a and 22b function as radiation plates, and the metal cases 52 and 53 coupled tothe respective wiring electrodes 22 a and 22 b also function as theradiation plates. Thus, the radiation characteristics and the antennagain are improved.

Twelfth Preferred Embodiment

In the radio IC device according to a twelfth preferred embodiment, aportion of the metal case 50 is disposed on the ground electrode 23connected to the wiring electrode 22 a as in the fifth preferredembodiment (see FIG. 11), as shown in FIG. 20. The ground electrode 23and the metal case 50 are coupled to each other to function as aradiation plate.

Thirteenth Preferred Embodiment

In the radio IC device according to a thirteenth preferred embodiment,the area of the loop electrode 25 provided as the second wiringelectrode is increased as shown in FIG. 21 so that the loop electrode 25can be used as a ground electrode 23 or a power supply electrode. Themetal case 50 is disposed on a portion of the loop electrode 25. In thethirteenth preferred embodiment, the loop electrode 25 and the metalcase 50 function as a radiation plate.

Fourteenth Preferred Embodiment

In the radio IC device according to a fourteenth preferred embodiment,the loop electrode 25 provided as the second wiring electrode and theground electrode 23 are integrated to function as a radiation plate, anda metal case 54 electrically connected to the ground electrode 23 isdisposed on the printed wiring board 20 so as to cover the radiationplate, as shown in FIG. 22. The metal case 54 has a notch 55 in a regioncorresponding to the loop electrode 25 when viewed from above. Since amagnetic field is generated around the loop electrode 25, the magneticfield is radiated out of the metal case 54 through the notch 55 over theloop electrode 25. Thus, the radiation characteristics are improved. Themetal case 54 may be disposed so as to cover at least one of otherelectronic components (not shown).

Fifteenth Preferred Embodiment

In the radio IC device according to a fifteenth preferred embodiment, aground electrode 101 including an opening 102 is disposed on a printedwiring board 100, and a pair of loop electrodes 103 functioning asinductance elements are provided in the opening 102, as shown in FIG.23. The electromagnetic coupling module 1 (or radio IC chip 5 alone) iscoupled to the end of each loop electrode 103. The printed wiring board100 includes switching modules 105, ICs 106, and other elements 107,such as chip resistors and chip capacitors thereon. The printed wiringboard 100 is covered with a shielding case 109.

A USB connector 110 is connected to the printed wiring board 100. Themetal portion of the connector 110 is electrically connected to theground electrode 101 and functions as a radiation plate of theelectromagnetic coupling module 1. The ground electrode 101 includes aslit 104 in the vicinity of the connector 110, so that electromagneticwaves through the connector 110 can efficiently propagate to the loopelectrodes 103.

FIG. 24 shows a state before the shielding case 109 and the connector110 are disposed on the printed wiring board 100. In this state, theground electrode 101 functions as a radiation plate. Thus, the structureof the fifteenth preferred embodiment can function as a radio IC devicefrom a stage shown in FIG. 24 to the final stage shown in FIG. 23 of themanufacturing process.

Sixteenth Preferred Embodiment

In the radio IC device according to a sixteenth preferred embodiment,the shielding wire 111 a of a coaxial cable (power supply cable) 111 iselectrically connected to the ground electrode 101 disposed on theprinted wiring board 100, as shown in FIG. 25. The other structure issubstantially the same as in the fifteenth preferred embodiment.

In the sixteenth preferred embodiment, the shielding wire 111 a of thecoaxial cable 111 electrically connected to the ground electrode 101functions as a radiation plate of the electromagnetic coupling module 1.Since the shielding wire 111 a is relatively long, communication can beperformed even with weak electromagnetic waves.

Seventeenth Preferred Embodiment

In the radio IC device according to a seventeenth preferred embodiment,a slot case 112 of a USB card is electrically connected to the groundelectrode 101 disposed on the printed wiring board 100, as shown in FIG.26. The other structure is substantially the same as in the fifteenthpreferred embodiment. The slot case 112 is a metal component, and iselectrically continued to the ground electrode 101 to function as aradiation plate of the electromagnetic coupling module 1.

Eighteenth Preferred Embodiment

In the radio IC device according to an eighteenth preferred embodiment,the metal case of a battery 113 is electrically connected to the groundelectrode 101 disposed on the printed wiring board 100, as shown in FIG.27. The other structure is substantially the same as in the fifteenthpreferred embodiment. The metal case of the battery 113 is electricallyconnected to the ground electrode 101 to function as the radiation plateof the electromagnetic coupling module 1.

Nineteenth Preferred Embodiment

In the radio IC device according to a nineteenth preferred embodiment,the shielding case 109 of the fifteenth preferred embodiment shown inFIG. 23 is electrically connected to the ground electrode 101 through aconductor portion 109 a, as shown in FIG. 28. The other structure issubstantially the same as in the fifteenth preferred embodiment. In thenineteenth preferred embodiment, the shielding case 109 as well as themetal portion of the connector 110 functions as a radiation plate. Theground electrode 101 includes a slit 104 in the vicinity of theconductor portion 109 a, so that electromagnetic waves through theshielding case 109 can efficiently propagate to the loop electrode 103.

Twentieth Preferred Embodiment

In the radio IC device according to a twentieth preferred embodiment,the shielding case 109 of the sixteenth preferred embodiment shown inFIG. 25 is electrically connected to the ground electrode 101 through aconductor portion 109 a, as shown in FIG. 29. The other structure issubstantially the same as in the sixteenth preferred embodiment. In thetwentieth preferred embodiment, the shielding case 109 as well as theshielding wire 111 a of the coaxial cable 111 functions as a radiationplate. The ground electrode 101 includes a slit 104 in the vicinity ofthe conductor portion 109 a, so that electromagnetic waves through theshielding case 109 can efficiently propagate to the loop electrode 103.

Twenty First Preferred Embodiment

In the radio IC device according to a twenty first preferred embodiment,a ground electrode 121 disposed on a printed wiring board 120 includes aslit opening 121 a, as shown in FIG. 30. A wiring electrode (hereinafterreferred to as power line 122) is provided in the slit opening 121 a. Apower supply cable 128 is connected to the ground electrode 121, andanother power supply cable 129 is connected to the power line 122. Inthis state, the electromagnetic coupling module 1 is bonded on the powerline 122. The printed wiring board 120 is covered with a shielding case127 and the power supply cables 128 and 129 extend a relatively longdistance out of the shielding case 127. The power line 122 is providedwith a capacitor 125 to reject high-frequency noises, a voltageregulator 126 and other interference to stabilize the voltage.

The electromagnetic coupling module 1 includes a feed circuit board 130including a coil (inductance element) 131, a radio IC chip 5 on the feedcircuit board 130, and a resin protecting member 141 covering the feedcircuit board 130 and the radio IC chip 5, as shown in FIG. 32. The coil131 is arranged such that the coil axis extends parallel orsubstantially parallel to the power line 122, and each end of which iselectrically connected to the radio IC chip 5.

In the operation principle of the radio IC device of the twenty firstpreferred embodiment, when the power supply cable 129 receives magneticwaves from a reader/writer (not shown), the power line 122 generates acurrent, as shown in FIG. 31. The current flows to the ground electrode121 through the capacitor 125 to generate a magnetic field φ at thepower line 122. The magnetic field φ is coupled to the coil 131 of thefeed circuit board 130, thus operating the radio IC chip 5.

In the twenty first preferred embodiment, the power supply cable 129functions as a radiation plate. Also, the power line 122 functions as aradiation plate in the course of the manufacturing process in which theshielding case 127 or the power supply cable 129 is not provided. Thepower supply cable 129 may be directly connected to the reader/writer.

Twenty Second Preferred Embodiment

In the radio IC device according to a twenty second preferredembodiment, the feed circuit board 130 of the electromagnetic couplingmodule 1 is provided with a matching circuit/resonance circuit 132 inaddition to the coil 131, as shown in FIG. 33. The other structure issubstantially the same as in the twenty first preferred embodiment. Thetwenty second preferred embodiment produces substantially the sameeffects as the twenty first preferred embodiment. In particular, whenthe circuit 132 is a matching circuit, the matching with the coil 131can be provided, so that the radio IC chip 5 can be operated even at alow power. When the circuit 132 is a resonance circuit, the radio ICchip can be frequency-selective, and accordingly, the variation infrequency can be reduced. Thus, the radio IC chip can work in a widerange of frequencies.

Twenty Third Preferred Embodiment

In the radio IC device according to a twenty third preferred embodiment,the feed circuit board 130 of the electromagnetic coupling module 1 isprovided with a pair of external terminal electrodes 133 on the rearsurface thereof, as shown in FIG. 34. The other structure issubstantially the same as in the twenty first preferred embodiment. Thetwenty third preferred embodiment produces substantially the sameeffects as the twenty first preferred embodiment. In particular, theexternal terminal electrodes 133 provided on the rear surface of thefeed circuit board 130 allow the electromagnetic coupling module 1 to bejoined to the power line 122 with solder, for example. Thus, theelectromagnetic coupling module 1 can be mounted simultaneously withother surface mount components. Alternatively, only a single externalterminal electrode 133 may be formed at substantially the center of therear surface of the feed circuit board 130.

Twenty Fourth Preferred Embodiment

In the radio IC device according to a twenty fourth preferredembodiment, the feed circuit board 130 of the electromagnetic couplingmodule 1 is provided with a pair of external terminal electrodes 133 onthe rear surface thereof, as shown in FIG. 35. In addition, a conductor134 is disposed within the feed circuit board 130 on the rear surfaceside, and the power line 122 is cut under the conductor 134. The otherstructure is substantially the same as in the twenty first and thetwenty third preferred embodiment. The twenty fourth preferredembodiment produces substantially the same effects as the twenty firstand the twenty third preferred embodiment. Since the current running inthe power line 122 is conducted to flow near the coil 131 by theconductor 134, the degree of coupling is improved, and accordingly, theradio IC chip can operate at a low power. In addition, the variation incoupling degree is reduced.

Twenty Fifth Preferred Embodiment

In the radio IC device according to a twenty fifth preferred embodiment,an auxiliary substrate 140 is provided on which an electromagneticcoupling module 1 is mounted, as shown in FIG. 36. A coupling electrode141 having an opening 142 is provided on the auxiliary substrate 140,and a pair of loop electrodes 143 functioning as inductance elements isprovided in the opening 142. The electromagnetic coupling module 1 (orradio IC chip 5 alone) is coupled to the end of each loop electrode 143.The other structure is substantially the same as in the twenty firstpreferred embodiment.

In the twenty fifth preferred embodiment, the electromagnetic couplingmodule 1 is coupled to the loop electrodes 143, and in addition, thecoupling electrode 141 is coupled to the power line 122. Substantiallythe same effects are produced as in the twenty first preferredembodiment. In particular, the use of the auxiliary substrate 140enables the use of a large coupling electrode 141 or the increase of thecoil 131 in the feed circuit board 130. Thus, the degree of coupling tothe power line 122 can be increased. In addition, the coupling electrode141 on the auxiliary substrate 140 can function as the radiation plateby itself, and can be disposed anywhere on the printed wiring board 120.

Twenty Sixth Preferred Embodiment

In the radio IC device according to a twenty sixth preferred embodiment,a power line 122 on which the electromagnetic coupling module 1 ismounted is arranged so as to extend a relatively long distance in thelateral direction along an edge of the printed wiring board 120, asshown in FIG. 37. The other structure is substantially the same as inthe twenty first preferred embodiment (see FIG. 30). The twenty sixthpreferred embodiment produces substantially the same effects as thetwenty first preferred embodiment. The lengthened power line 122functions as the radiation plate and allows the radio IC device tofunction before the shielding case 127 or the power supply cable 129 isprovided.

Twenty Seventh Preferred Embodiment

In the radio IC device according to a twenty seventh preferredembodiment, the power line 122 shown in FIG. 37 is branched so as toextend a relatively long distance in the lateral direction along an edgeof the printed wiring board 120, as shown in FIG. 38. The otherstructure is substantially the same as in the twenty first and thetwenty sixth preferred embodiment. Since the power line 122 functioningas a radiation plate of the twenty seventh preferred embodiment islonger than that of the twenty sixth preferred embodiment,electromagnetic waves can be more efficiently transmitted and received,and the operation can be performed at a low power. Preferably, the powerline 122 has a length that enables it to resonate.

Twenty Eighth Preferred Embodiment

In the radio IC device according to a twenty eighth preferredembodiment, the extensions of the power line 122 shown in FIG. 38 areconfigured in a meandering arrangement, as shown in FIG. 39. The otherstructure is substantially the same as in the twenty first preferredembodiment. In the twenty eighth preferred embodiment, the power line122 functioning as a radiation plate is relatively large, andaccordingly, electromagnetic waves can be transmitted and received moreefficiently.

Twenty Ninth Preferred Embodiment

In the radio IC device according to a twenty ninth preferred embodiment,the ground electrode 121 disposed on the printed wiring board 120 has arelatively large opening 121 b in which a plurality of line electrodes145 are arranged in parallel or substantially in parallel with eachother. The line electrodes 145 are connected to signal lines 146, suchas for a USB, and one of which is coupled to the electromagneticcoupling module 1, as shown in FIG. 40. A regulator 126 is disposedbetween the line electrodes 145 and the ground electrode 121.

In the twenty ninth preferred embodiment, the signal lines 146 functionsas a radiation plate, and substantially the same effects are produced asin the twenty first preferred embodiment and other preferredembodiments. In particular, the radio IC device can function even thoughit is driven by a battery and does not have a power supply cable.

Thirtieth Preferred Embodiment

In the radio IC device according to a thirtieth preferred embodiment,the electrode 121 disposed on the printed wiring board 120 includes aslit opening 121 a, as shown in FIG. 41. An antenna line 151 is disposedin the slit opening 121 a, and an antenna wire 152 is connected to theantenna line 151. The electromagnetic coupling module 1 is coupled tothe antenna line 151. The regulator 126 is disposed between the antennaline 151 and the ground electrode 121.

In the thirtieth preferred embodiment, the antenna wire 152 functions asa radiation plate, and substantially the same effects are produced as inthe twenty first preferred embodiment and other preferred embodiments.The electromagnetic coupling module 1 is provided with a resonancecircuit or a matching circuit so that energy is transmitted to the radioIC chip 5 only at a frequency at which the IC chip 5 operates as anRFID, thus preventing interference with the operation of the antenna. Inthe present preferred embodiment, the antenna wire 152 intended toreceive electromagnetic waves is efficiently used as a radiation plate.Accordingly, the operation can be performed at a low power.

Thirty First Preferred Embodiment

In the radio IC device according to a thirty first preferred embodiment,an anti-ESD device, such as a varistor 153, for example, is disposedbetween the power line 122 and the ground electrode 121, and theelectromagnetic coupling module 1 is disposed downstream from thevaristor 153, as shown in FIG. 42. The other structure is substantiallythe same as in the twenty first preferred embodiment (see FIG. 30). Thethirty first preferred embodiment produces substantially the sameeffects as the twenty first preferred embodiment. In particular, thepresence of the varistor 153 improves the electrostatic surgeresistance.

Thirty Second Preferred Embodiment

The radio IC device according to a thirty second preferred embodiment issubstantially the same as that of the twenty first preferred embodiment(see FIG. 30) in that the electromagnetic coupling module 1 is coupledto the power line 122, as shown in FIG. 43. The two preferredembodiments have a difference in that the coil 131 provided on the feedcircuit board 130 is disposed such that the coil axis extends in thedirection perpendicular or substantially perpendicular to the power line122. The thirty second preferred embodiment produces substantially thesame effects as the twenty first preferred embodiment. In particular,the coil 131 is arranged such that the coil axis extends in thedirection in which the sheets of the feed circuit board 130 are stacked,and this facilitates the formation of the coil 131.

Thirty Third Preferred Embodiment

In the radio IC device according to a thirty third preferred embodiment,the ground electrode 121 disposed on the printed wiring board 120includes a slit opening 121 a, as shown in FIG. 44. A power line 122 isdisposed in the slit opening 121 a. A power supply cable 128 isconnected to the ground electrode 121, and another power supply cable129 is connected to the power line 122. In this state, anelectromagnetic coupling module 1 is bonded across the region betweenthe power line 122 and the ground electrode 121. The printed wiringboard 120 is covered with a shielding case 127 and the power supplycables 128 and 129 extend long out of the shielding case 127. The powerline 122 is provided with a capacitor 125 for rejecting high-frequencynoises, a voltage regulator 126 and the like to stabilize the voltage.

The electromagnetic coupling module 1 includes the radio IC chip 5 and afeed circuit board 160, as shown in FIG. 45. The feed circuit board 160includes inductance elements L11 and L12 magnetically coupled to eachother, and a resonance circuit having a predetermined resonancefrequency with capacitors defined by an internal electrode 161 and aground electrode 121 and by an internal electrode 162 and a power line122. The radio IC chip 5 is electrically connected to the resonancecircuit with solder bumps. In FIG. 45, reference numeral 156 designatesan adhesive, and reference numeral 166 designates a protective layer forthe solder bumps.

In the operation principle of the radio IC device of the thirty thirdpreferred embodiment, when the power supply cable 129 receives magneticwaves from a reader/writer (not shown), the power line 122 generates acurrent. In this instance, the power line 122 and the ground electrode121 have a potential difference therebetween, because of the presence ofan inductance component (in a coil form) as shown in FIG. 44 in view ofhigh frequency. The occurrence of the potential difference enables theinternal electrodes 161 and 162 of the feed circuit board 160 to beelectromagnetically coupled to the ground electrode 121 and the powerline 122, so that a signal operates the radio IC chip 5 through theresonance circuit.

In the thirty third preferred embodiment, the power supply cable 129functions as a radiation plate, and substantially the same effects areproduced as in the twenty first preferred embodiment (see FIG. 30).Since the feed circuit board 160 includes the resonance circuitincluding the inductance elements L11 and L12 and the capacitor, thefeed circuit board functions of matching with the radio IC chip 5 and afunction of selecting frequency. Thus, signals can be transmitted in awide range of frequencies. The electromagnetic coupling module 1 may bereplaced with only a radio IC chip 5.

Thirty Fourth Preferred Embodiment

In the radio IC device according to thirty fourth preferred embodiment,the resonance circuit provided in the feed circuit board 160 of theelectromagnetic coupling module 1 is defined by inductance elements L11,L12 and L13 coupled to each other, as shown in FIG. 46. In the thirtyfourth preferred embodiment, the other structure is substantially thesame as in the thirty third preferred embodiment, and substantially thesame effects are produced as in the thirty third preferred embodiment.In particular, since the resonance circuit is bilaterally symmetrical,the electromagnetic coupling module 1 can be mounted without consideringthe directivity.

Thirty Fifth Preferred Embodiment

In the radio IC device according to a thirty fifth preferred embodiment,external terminal electrodes 163 and 164 that oppose the internalelectrodes 161 and 162 are provided on the rear surface of the feedcircuit board 160, as shown in FIG. 47. In the thirty fifth preferredembodiment, the other structure is substantially the same as in thethirty fourth preferred embodiment, and substantially the same effectsare produced as in the thirty fourth preferred embodiment. By providingthe external terminal electrodes 163 and 164, the electromagneticcoupling module 1 can be bonded on the printed wiring board 120 withsolder, for example, and thus, can be mounted simultaneously with othersurface mount components.

Thirty Sixth Preferred Embodiment

In the radio IC device according to a thirty sixth preferred embodiment,a power line 122 on which the electromagnetic coupling module 1 ismounted is provided so as to extend a relatively long distance in thelateral direction along an edge of the printed wiring board 120, asshown in FIG. 48. The other structure is substantially the same as inthe thirty third preferred embodiment (see FIG. 44). The thirty sixthpreferred embodiment produces substantially the same effects as thethirty third preferred embodiment. The lengthened power line 122 canmore effectively function as the radiation plate and enables the radioIC device to function before the shielding case 127 or the power supplycable 129 is provided.

Thirty Seventh Preferred Embodiment

The radio IC device according to a thirty seventh preferred embodiment,the extension of the power line 122 shown in FIG. 48 is configured in ameandering arrangement, as shown in FIG. 49. The other structure issubstantially the same as in the thirty third preferred embodiment. Inthe thirty seventh preferred embodiment, the power line 122 functioningas a radiation plate is relatively large, and accordingly,electromagnetic waves can be transmitted and received more efficiently.

Thirty Eighth Preferred Embodiment

In the radio IC device according to a thirty eighth preferredembodiment, the power line 122 shown in FIG. 48 is branched so as toextend a relatively long distance in the lateral direction along an edgeof the printed wiring board 120, as shown in FIG. 50. The otherstructure is substantially the same as in the thirty third and thethirty sixth preferred embodiment. Since the power line 122 functioningas a radiation plate of the thirty eighth preferred embodiment is longerthan that of the thirty sixth preferred embodiment, electromagneticwaves can be more efficiently transmitted and received, and theoperation can be performed at a low power. Preferably, the power line122 has a length which enables it to resonate.

Thirty Ninth Preferred Embodiment

In the radio IC device according to a thirty ninth preferred embodiment,the extensions to both sides of the power line 122 are configured in ameandering arrangement, as shown in FIG. 51. The other structure issubstantially the same as in the thirty third preferred embodiment. Inthe thirty ninth preferred embodiment, the power line 122 functioning asa radiation plate is relatively large, and accordingly, electromagneticwaves can be transmitted and received more efficiently.

Fortieth Preferred Embodiment

In the radio IC device according to a fortieth preferred embodiment, aportion of the power line 122 is disposed under the printed wiring board120, as shown in FIG. 52, and the electromagnetic coupling module 1 ismounted across the region between the power line 122 exposed at thesurface and the ground electrode 121. The power supply cable 129 isconnected to an end 122 a of the power line exposed at the surface.

In the fortieth preferred embodiment, the other structure issubstantially the same as in the thirty third preferred embodiment, andsubstantially the same effects are produced as in the thirty thirdpreferred embodiment. In particular, since the power line 122 ispartially disposed under the printed wiring board 120, the flexibilityof wiring on the surface is improved.

Forty First Preferred Embodiment

In the radio IC device according to a forty first preferred embodiment,the power line 122 is bent in a substantial C shape and both ends of theelectromagnetic coupling module 1 are connected to the bent portions, asshown in FIG. 53. In the forty first preferred embodiment, the otherstructure is substantially the same as in the thirty third preferredembodiment, and substantially the same effects are produced as in thethirty third preferred embodiment.

Forty Second Preferred Embodiment

In the radio IC device according to a forty second preferred embodiment,the electromagnetic coupling module 1 is mounted across the power line122 from one end of the ground electrode 121 to the opposing end, asshown in FIG. 54. The other structure is substantially the same as inthe thirty third preferred embodiment, and the electromagnetic couplingmodule 1 is operated by a difference in potential produced on the groundelectrode 121.

In the forty second preferred embodiment, the feed circuit board 160includes a coil 167 coupled by a magnetic field φ generated by thecurrent flowing in the power line 122 in addition to the inductanceelements L11 and L12, as shown in FIG. 55. The coil 167 is connected inseries with the inductance elements L11 and L12, and is thus operated bythe current flowing in the power line 122. In other words, the coil 167functions as a matching inductance element. Even if the power linecannot sufficiently receive magnetic waves, the ground electrode 121 canfunction as a radiation plate, and even if either element of the feedcircuit is broken, the other element ensures the operation.

Forty Third Preferred Embodiment

In the radio IC device according to a forty third preferred embodiment,a portion 121 c of the ground electrode 121 coupled to the feed circuitof the electromagnetic coupling module 1 is formed in a loop, as shownin FIG. 56. The other structure is substantially the same as in thethirty third and the forty second preferred embodiment, andsubstantially the same effects are produced as in the thirty third andthe forty second preferred embodiments. By forming the portion 121 c ofthe ground electrode 121 coupled to the resonance circuit in a loop, theantenna gain is improved, and the radio IC chip 5 can be operated at alow power.

Forty Fourth Preferred Embodiment

In the radio IC device according to a forty fourth preferred embodiment,the ground electrode 121 disposed on the printed wiring board 120 has arelatively large opening 121 b in which a plurality of line electrodes145 are provided in parallel with each other. The line electrodes 145are connected to signal lines 146, such as for a USB, and theelectromagnetic coupling module 1 is disposed across the region betweenthe ground electrode 121 and one of the line electrodes 145 to becoupled to that one line electrode, as shown in FIG. 57. A regulator 126is disposed between the line electrodes 145 and the ground electrode121.

In the forty fourth preferred embodiment, the signal lines 146 functionas a radiation plate using the difference in potential between the lineelectrode 145 and the ground electrode 121, and substantially the sameeffects are produced as in the thirty third and the twenty ninthpreferred embodiment.

Forty Fifth Preferred Embodiment

In the radio IC device according to a forty fifth preferred embodiment,the electromagnetic coupling module 1 is coupled so as to be disposedacross the region between two adjacent line electrodes 145, as shown inFIG. 58. The other structure is substantially the same as in the fortyfourth preferred embodiment and substantially the same effects areproduced as in the forty fourth preferred embodiment. The forty fifthpreferred embodiment uses the difference in potential between the twoadjacent line electrodes 145.

Forty Sixth Preferred Embodiment

In the radio IC device according to a forty sixth preferred embodiment,the ground electrode 121 disposed on the printed wiring board 120includes a slit opening 121 a, as shown in FIG. 59. An antenna line 151is disposed in the slit opening 121 a, and an antenna wire 152 isconnected to the antenna line 151. The electromagnetic coupling module 1is coupled so as to be disposed across a region between the antenna line151 and the ground electrode 121. The regulator 126 is disposed betweenthe antenna line 151 and the ground electrode 121. In the forty sixthpreferred embodiment, the antenna wire 152 functions as the radiationplate, and substantially the same effects are produced as in the thirtythird and the thirtieth preferred embodiment.

Forty Seventh Preferred Embodiment

In the radio IC device according to a forty seventh preferredembodiment, an auxiliary substrate 170 is provided on which theelectromagnetic coupling module 1 is mounted, as shown in FIG. 60. Acoupling electrode 171 is provided on the auxiliary substrate 170, and apair of loop electrodes 173 functioning as inductance elements isprovided for the coupling electrode 171. The electromagnetic couplingmodule 1 (or radio IC chip 5 alone) is coupled to each end of the loopelectrodes 173. The ends of the coupling electrode 171 are connected tothe power line 122 and the ground electrode 121 with solder 175. Theother structure is substantially the same as in the thirty thirdpreferred embodiment.

In the forty seventh preferred embodiment, the electromagnetic couplingmodule 1 is coupled to the loop electrodes 173, and in addition, thecoupling electrode 171 is disposed across the region between the powerline 122 and the ground electrode 121 so as to be coupled to the powerline 122 and the ground electrode 121. Thus, substantially the sameeffects are produced as in the thirty third preferred embodiment. Inparticular, the use of the auxiliary substrate 170 enables even a smallelectromagnetic coupling module 1 to be disposed across the regionbetween the power line 122 and the ground electrode 121. In addition, aninductance element or other suitable element may be provided on theauxiliary substrate 170 in order to reduce the size of the feed circuitboard 160. Furthermore, the coupling electrode 171 on the auxiliarysubstrate 170 functions as a radiation plate by itself.

Forty Eighth Preferred Embodiment

In the radio IC device according to a forty eighth preferred embodiment,an anti-ESD device, such as a varistor 153, for example, is disposedbetween the power line 122 and the ground electrode 121, and anelectromagnetic coupling module 1 is disposed downstream from thevaristor 153, as shown in FIG. 61. The other structure is substantiallythe same as in the thirty third preferred embodiment (see FIG. 44). Theforty eighth preferred embodiment produces substantially the sameeffects as the thirty third and the thirty first preferred embodiment.

Forty Ninth Preferred Embodiment

In the radio IC device according to a forty ninth preferred embodiment,a ground electrode 181 disposed on a printed wiring board 180 includesan opening 182 to define a loop electrode 183, and the electromagneticcoupling module 1 is mounted on the loop electrode 183, as shown in FIG.62. The electromagnetic coupling module 1 includes the radio IC chip 5and a feed circuit board 190. The feed circuit board 190 includes a coil(inductance element) 191, as shown in FIG. 64. The coil 191 is arrangedsuch that the coil axis extends parallel or substantially parallel tothe loop electrode 183, and each end of the coil 191 is electricallyconnected to the radio IC chip 5.

In the operation principle of the radio IC device of the forty ninthpreferred embodiment, when the ground electrode 181 receives magneticwaves from a reader/writer (not shown), the loop electrode 183 generatesa current. The magnetic field φ generated by the current is coupled tothe coil 191 of the feed circuit board 190, thus operating the radio ICchip 5. In this instance, preferably, the electromagnetic couplingmodule 1 is arranged such that a magnetic field φ intersects only oneside of the coil 191. In addition to the coil 191, a matchingcircuit/resonance circuit 192 may be provided within the feed circuitboard 190, as shown on FIG. 65.

The elements 105, 106 and 107 disposed on the printed wiring board 180are substantially the same as in the fifteenth preferred embodiment (seeFIG. 23).

Fiftieth Preferred Embodiment

In the radio IC device according to a fiftieth preferred embodiment, theloop electrode 183 provided on the ground electrode 181 is bent in asubstantial C shape, and the electromagnetic coupling module 1 ismounted such that the coil 191 is disposed along the loop electrode 183,as shown in FIG. 66. The other structure is substantially the same as inthe forty ninth preferred embodiment.

The fiftieth preferred embodiment produces substantially the sameeffects as the forty ninth preferred embodiment. In particular, thedegree of coupling between the coil 191 and the loop electrode 183 isimproved and the energy can be efficiently transmitted. In addition, theelectromagnetic coupling module 1 does not significantly protrude fromthe edge of the printed wiring board 180.

Fifty First Preferred Embodiment

In the radio IC device according to a fifty first preferred embodiment,the electromagnetic coupling module 1 is disposed in a reverseorientation to that in the forty ninth preferred embodiment (see FIG.62) on the printed wiring board 180, as shown in FIG. 67. The otherstructure is substantially the same as in the forty ninth preferredembodiment, and substantially the same effects are produced as in theforty ninth preferred embodiment. In particular, it is an advantage thatthe electromagnetic coupling module 1 does not significantly protrudefrom the edge of the printed wiring board 180.

Fifty Second Preferred Embodiment

In the radio IC device according to a fifty second preferred embodiment,the feed circuit board 190 includes a coil 191 arranged such that thecoil axis extends perpendicular or substantially perpendicular to theloop electrode 183, as shown in FIG. 68. The fifty second preferredembodiment produces substantially the same effects as the forty ninthpreferred embodiment. In particular, the coil 191 is arranged such thatthe coil axis extends in the direction in which the sheets of the feedcircuit board 190 are stacked, and this facilitates the formation of thecoil 191.

Fifty Third Preferred Embodiment

In the radio IC device according to a fifty third preferred embodiment,the electromagnetic coupling module 1 is mounted at an edge of theground electrode 181 without providing a loop electrode 183 on theground electrode 181, as shown in FIG. 69. The other structure issubstantially the same as in the forty ninth preferred embodiment, andsubstantially the same effects are produced as in the forty ninthpreferred embodiment. The electromagnetic coupling module 1 is operatedby being coupled with a magnetic field generated by the current flowingin the edge of the ground electrode 181.

Fifty Fourth Preferred Embodiment

In the radio IC device according to a fifty fourth preferred embodiment,a notch 184 is provided in the printed wiring board 180, and the groundelectrode 181 includes a loop electrode 183 at the edge around the notch184, as shown in FIG. 70. The other structure is substantially the sameas in the forty ninth preferred embodiment, and substantially the sameeffects are produced as in the forty ninth preferred embodiment.

Fifty Fifth Preferred Embodiment

In the radio IC device according to a fifty fifth preferred embodiment,the electromagnetic coupling module 1 is arranged in a corner of theground electrode 181 as shown in FIG. 71, unlike the fifty thirdpreferred embodiment in which the electromagnetic coupling module 1 isdisposed substantially at the center of an edge of the ground electrode181. The other structure is substantially the same as in the forty ninthand the fifty third preferred embodiment, and substantially the sameeffects are produced as in the forty ninth and fifty third preferredembodiment.

If the ground electrode 181 does not include the loop electrode 183, theelectromagnetic coupling module 1 can be disposed anywhere on the edgeof the ground electrode 181. Alternatively, a notch may be provided inthe corner of the printed wiring board 180 on which the electromagneticcoupling module 1 is disposed, as disclosed in the fifty fourthpreferred embodiment, and the ground electrode 181 has a loop electrodeat the edge around the notch.

Fifty Sixth Preferred Embodiment

In the radio IC device according to a fifty sixth preferred embodiment,a coil 195 in a feed circuit board 190 has a substantial FIG. 8 shape,as shown in FIG. 72, and the other structure is substantially the sameas in the forty ninth preferred embodiment (see FIG. 62). Theelectromagnetic coupling module 1 is arranged on the printed wiringboard 180 such that the magnetic flux φ generated from the loopelectrode 183 can pass through the loops of the coil 195 functioning asinductance elements, as shown in FIG. 73. In the fifty sixth preferredembodiment, consequently, the ground electrode 181 functioning as aradiation plate and the electromagnetic coupling module 1 can be highlycoupled.

Modification of Electromagnetic Coupling Module

The electromagnetic coupling module 1 may preferably include a squarefeed circuit board 200, as shown in FIG. 74. The coil 201 functioning asan inductance element also has a square shape. This electromagneticcoupling module 1 can be applied to any preferred embodiment of thepresent invention.

Fifty Seventh Preferred Embodiment

In the radio IC device according to a fifty seventh preferredembodiment, a slit 185 is provided in the ground electrode 181 disposedon the printed wiring board 180, extending from the edge to theapproximate center. The slit 185 has an opening 185 a at the endthereof, and the electromagnetic coupling module 1 is disposed over theopening 185 a, as shown in FIG. 75. The coil 191 provided on the feedcircuit board 190 and the opening 185 a have substantially the sameshape in plan view.

In the fifty seventh preferred embodiment, the surrounding of theopening 185 a functions as a loop electrode to be magnetically coupledto the coil 191. The presence of the slit 185 improves the concentrationof the current produced by the electromagnetic waves received by theground electrode 181 around the opening 185 a to generate a strongmagnetic field, thus improving the degree of coupling.

The slit 185 does not necessarily communicate with the edge of theground electrode 181. If the slit 185 is to be arranged according to thedesign of the printed wiring board 180, another slit is not necessarilyprovided for the electromagnetic coupling module 1.

In the radio IC device according to preferred embodiments of the presentinvention, the feed circuit board may preferably have a resonancecircuit through which the radio IC is operated by the signal received bythe radiation plate, and through which the answer signal from the radioIC is radiated from the radiation plate to the outside. The feed circuitboard may include a matching circuit.

The inductance element may preferably be defined by a spiral electrode,for example, and the spiral electrode may be coupled with a magneticfield generated at the wiring electrode on the wiring board. The wiringelectrode and the ground electrode on the wiring board may be isolatedfrom each other, and the feed circuit board may be disposed across aregion between the wiring electrode and the ground electrode. If thecase is a metal, the case may function as a radiation plate by itself.If the case is non-conductive, an electroconductive electrode film maybe formed on the case and the electrode film is used as the radiationplate.

The printed wiring board may preferably include an electromagneticcoupling module and other electronic components, and a case alsodefining the radiation plate is disposed so as to cover the highfrequency device and other electronic components. The printed wiringboard may include a second wiring electrode for coupling the feedcircuit and the radiation plate. In particular, if the second wiringelectrode is in a loop, the impedances can be matched between the radioIC and the radiation plate without providing an additional matchingportion, and the signal transmission efficiency can be improved betweenthe radio IC and the radiation plate. The loop electrode may be formedin an auxiliary substrate disposed on the feed circuit board. Aplurality of printed wiring boards may be used, and a high frequencydevice is disposed on at least one of the printed wiring boards. A casemay be arranged so as to cover the high frequency device and at leastone of other electronic components.

The printed wiring board may include a second wiring electrode arrangedto couple the feed circuit and the radiation plate, and a case may bearranged so as to cover all the electronic components and high frequencydevice mounted on the printed wiring board. The second wiring electrodemay function as a portion of the radiation plate. In this instance, theradiation characteristics can be improved, and the directivity can bechanged depending on the arrangement of the second wiring electrode. Atleast a portion of the electronic components may function as a portionof a radiation plate to improve the radiation characteristics.

The printed wiring board may include a ground electrode, and a secondwiring electrode may be electrically connected to the ground electrode.By using the ground electrode having a large area as a radiation plate,the radiation characteristics can further be improved.

The second wiring electrode may be provided on the surface of or withinthe printed wiring board. The printed wiring board may be made of aresin or a ceramic, for example.

An external electrode coupled to the feed circuit may be formed on thesurface of the feed circuit board.

The feed circuit board may be made of a ceramic or liquid crystalpolymer multilayer substrate, or a flexible substrate, for example. Theuse of a multilayer substrate enables an inductance element or acapacitance element to be arranged precisely within the feed circuitboard, thus improving the flexibility in the formation of electrodes.The use of a flexible substrate facilitates the reduction of thethickness or profile of the feed circuit board.

The radio IC may be rewritable as well as storing information of thecommodity on which the radio IC device is attached, and may have otherfunctions in addition to the function for an RFID system.

The radio IC device according to the present invention is not limited tothe above-described preferred embodiments, and various modifications maybe made without departing from the scope of the present invention.

For example, various types of resonance circuit or matching circuit maybe used. The materials used for the external electrode and the feedcircuit board in the above-described preferred embodiments are describedas examples, and any material can be used as long as it has desiredproperties. The radio IC chip can be mounted on the feed circuit boardby any method other than using a metal bump. The radio IC chip and thefeed circuit may be connected by electromagnetic coupling instead ofelectrical direct connection. The feed circuit board may include a radioIC.

The electromagnetic coupling module may be used in a variety ofapparatuses including household electrical appliances, such as TV setand refrigerator, without being limited to radio communicationapparatuses, such as cellular phone.

As described above, the present invention is useful in radio IC devicesused in RFID systems, and is particularly advantageous inminiaturization without reducing the radiation characteristics.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing the scope andspirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

1. (canceled)
 2. A radio IC device comprising: a radio IC arranged toprocess transmitted and received signals; an inductance elementelectrically connected to or electromagnetically coupled to the radioIC; and a radiation plate arranged so as to be coupled to the inductanceelement; wherein the radiation plate is defined by at least one of acase of an apparatus and a metal component disposed in the apparatus,and a loop electrode is provided in a portion of the at least one of thecase and the metal component; and the inductance element is coupled tothe loop electrode via a magnetic field.
 3. A radio IC devicecomprising: a radio IC arranged to process transmitted and receivedsignals; an inductance element electrically connected to orelectromagnetically coupled to the radio IC; and a radiation platearranged so as to be coupled to the inductance element; wherein theradiation plate is defined by at least one of a case of an apparatus anda metal component disposed in the apparatus; and the inductance elementis provided adjacent to an edge of the radiation plate, and coupled tothe radiation plate via a magnetic field generated by current flowing inthe edge of the radiation plate.
 4. The radio IC device according toclaim 2, wherein the radiation plate includes a notch provided therein,and an edge of the radiation plate which is located around the notchdefines the loop-shaped electrode.
 5. The radio IC device according toclaim 2, wherein the metal component is a first wiring electrodedisposed in the apparatus, a shielding case, a wiring electrode on awiring board, a ground electrode on the wiring board, or a connectorconnected to the wiring electrode or the ground electrode.
 6. The radioIC device according to claim 3, wherein the metal component is a firstwiring electrode disposed in the apparatus, a shielding case, a wiringelectrode on a wiring board, a ground electrode on the wiring board, ora connector connected to the wiring electrode or the ground electrode.7. The radio IC device according to claim 2, wherein the inductanceelement is defined by a spiral electrode.
 8. The radio IC deviceaccording to claim 3, wherein the inductance element is defined by aspiral electrode.
 9. The radio IC device according to claim 7, whereinthe radiation plate includes an opening provided therein, and an edge ofthe radiation plate which is located around the opening functions as theloop-shaped electrode, and the spiral electrode and a portion of theopening are magnetically coupled with each other.
 10. The radio ICdevice according to claim 8, wherein the radiation plate includes anopening provided therein, and an edge of the radiation plate which islocated around the opening functions as the loop-shaped electrode, andthe spiral electrode and a portion of the opening are magneticallycoupled with each other.
 11. The radio IC device according to claim 2,wherein the case is made of a metal material, and the case itselffunctions as the radiation plate.
 12. The radio IC device according toclaim 3, wherein the case is made of a metal material, and the caseitself functions as the radiation plate.
 13. The radio IC deviceaccording to claim 2, wherein the case is made of a non-conductivematerial, an electrode film which is made of a conductive material isprovided on the case, and the electrode film functions as the radiationplate.
 14. The radio IC device according to claim 3, wherein the case ismade of a non-conductive material, an electrode film which is made of aconductive material is provided on the case, and the electrode filmfunctions as the radiation plate.